One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,6)(7,8)(9,10)(11,17)(12,16)(13,15)(14,19)(18,24)(20,22)(21,23)(25,26,29,31)(27,35,36,39)(28,38,32,33)(30,40,37,34)(1,3)(2,5)(4,7)(6,8)(9,11,13,19)(10,14,15,17)(12,20,21,18)(16,24,23,22)(26,31)(27,36)(33,38)(34,40)(2,6)(3,7)(25,27,37,33,29,36,30,38)(26,32,40,39,31,28,34,35)(10,15)(14,17)(16,23)(22,24)(25,28)(26,33)(27,34)(29,32)(30,39)(31,38)(35,37)(36,40) involution — undirected(3,7)(5,8)(9,12,13,21)(10,16,15,23)(11,18,19,20)(14,22,17,24)(27,36)(28,32)(33,38)(35,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.